1. Field
One or more embodiments of the invention relate to a ground plane of a printed circuit.
2. Background Information
Many multi-layer printed circuits, such as, for example, printed circuit boards, printed wiring boards, and flexible printed circuits, may include planes dedicated to providing ground and power.
The ground planes may include openings, such as, for example via holes and/or slots, defined therein. In some printed circuits, via holes may be conjoined to form larger openings. Depending upon their number and size, the openings may potentially limit, divert, or at least affect the flow of currents, such as, for example, signal return currents, that may flow in the ground plane. Return currents tend to flow directly under or over lines or traces in the overlying or underlying signal layers. However, current often does not flow across openings in the ground plane to an appreciable extent. Rather, the current may be diverted around the openings.
FIG. 1 shows a ground plane 100 having a slot 102 and conjoined via holes 104 defined therein. A first arrow 106 shows how a signal return current may be diverted around the slot. A second arrow 108 shows how a signal return current may be diverted around the conjoined via holes.
The diversion of current around an opening may enlarge a current loop area. The enlarged loop area may result in an increase in impedance, electromagnetic interference, and signal integrity return loss, to name just a few potential problems.